Semiconductor Memory Device Including Program Operation Status Flag Cells

1. A semiconductor memory device comprising: a memory cell array including a plurality of memory cells and one or more flag cells, each flag cell coupled to a unit of memory cells via a word line; a controller in communication with the memory cell array and configured to: select, from word lines coupled to the plurality of memory cells, a word line coupled to a set of target memory cells from the plurality of memory cells for programming; apply, to the selected word line, a series of programming pulses of increasing magnitude to raise threshold voltages of the set of target memory cells and program verification pulses to verify whether the threshold voltages of the set of target memory cells have been raised to above target threshold voltage levels; apply the series of programming pulses to the set of target memory cells; and upon determination that program operations on the set of target memory cells have not been verified as properly programmed after performing program and program verification operations for a predetermined number of iterations, apply one or more additional programming pulses for programming the one or more flag cells to indicate the program operations on the set of target memory cells have finally failed.

2. The semiconductor memory device of claim 1 , wherein the controller is further configured to, during a read operation of the semiconductor memory device that is turned on after a power loss, copy data read out from the set of target memory cells to memory cells different from the set of target memory cells, upon successful read of the data by an error correction engine.

3. The semiconductor memory device of claim 1 , wherein the controller is further configured to, during a read operation of the semiconductor memory device turned on after a power loss, process data read out from the set of target memory cells as erroneous data upon a determination that the one or more flag cells are programmed.

4. The semiconductor memory device of claim 1 , wherein the controller is further configured to, upon a determination that the one or more flag cells are programmed, designate the set of target memory cells as failed memory cells.

5. The semiconductor memory device of claim 1 , wherein the one or more additional programming pulses are applied after the predetermined number of iterations.

6. The semiconductor memory device of claim 1 , wherein the controller is further configured to: read data successfully from the plurality of memory cells by an error correction engine; and determine that the data successfully read by the error correction engine is erroneous, upon determination that the one or more flag cells associated with the plurality of memory cells are programmed by the one or more additional programming pulses.

7. The semiconductor memory device of claim 6 , wherein the controller is further configured to: upon determination that the one or more flag cells associated with the plurality of memory cells are programmed by the one or more additional programming pulses, perform a reprogramming operation on the plurality of memory cells.

8. A semiconductor memory device comprising: a memory cell array including a plurality of memory cells to store data and one or more flag cells to indicate whether program operations on the plurality of memory cells have finally failed after performing program and program verification operations for a predetermined number of iterations; a controller in communication with the memory cell array and configured to: determine whether the one or more flag cells are programmed to indicate the program operations on the plurality of memory cells associated with the one or more flag cells have finally failed; read data successfully from the plurality of memory cells by an error correction engine; and determine that the data successfully read by the error correction engine is erroneous, upon determination that the one or more flag cells associated with the plurality of memory cells are programmed.

9. The semiconductor memory device of claim 8 , wherein the controller is further configured to, upon a determination that the program operations on the plurality of memory cells have been verified as completed and that the data is successfully read by the error correction engine, process data read out from the plurality of memory cells as valid data.

10. The semiconductor memory device of claim 8 , wherein the controller is further configured to, upon a determination that the one or more flag cells associated with the plurality of memory cells are programmed to indicate the program operations on the plurality of memory cells have not been verified as completed and that the data is successfully read by the error correction engine, process data read out from the plurality of memory cells as erroneous data.

11. The semiconductor memory device of claim 8 , wherein the controller is further configured to, upon a determination that the one or more flag cells associated with the plurality of memory cells are programmed to indicate the program operations on the plurality of memory cells have not been verified as completed and that the data is successfully read by the error correction engine, designate the plurality of memory cells as failed memory cells.

12. The semiconductor memory device of claim 8 , wherein the controller is further configured to, upon a determination that the program operations on the plurality of memory cells have been verified as completed and that the data is not successfully read by the error correction engine, process data read out from the plurality of memory cells as erroneous data.

13. The semiconductor memory device of claim 8 , wherein the controller is further configured to, upon a determination that the one or more flag cells associated with the plurality of memory cells are programmed to indicate the program operations on the plurality of memory cells have not been verified as completed and that the data is not successfully read by the error correction engine, process data read out from the plurality of memory cells as erroneous data.

14. The semiconductor memory device of claim 8 , wherein the controller is further configured to, upon a determination that the one or more flag cells associated with the plurality of memory cells are programmed to indicate the program operations on the plurality of memory cells have not been verified as completed and that the data is not successfully read by the error correction engine, designate the plurality of memory cells as failed memory cells.

15. The semiconductor memory device of claim 8 , wherein the memory cell array further includes an additional flag cell to indicate the program operations on the plurality of memory cells have been verified as completed.

16. The semiconductor memory device of claim 15 , wherein, upon a determination that both the flag cells and the additional flag cells are not programmed and that the data is not successfully read by the error correction engine, process data read out from the plurality of memory cells as erroneous data.

17. The semiconductor memory device of claim 15 , wherein, upon a determination that both the flag cells and the additional flag cells are not programmed and that the data is successfully read by the error correction engine, copy data read out from the plurality of memory cells to memory cells different from the set of target memory cells.